The wine-making industry is closely regulated, an example of which is shown by the classification of wines in 26 U.S.C. 5381-5392. Standard wine is known as an extremely desirable wine of high quality. The term "standard wine" refers to a wine which has not been ameliorated (that is, diluted with water) and which has a light transmission value significantly unaltered by the manufacturing process, although high acid wines may be ameliorated in accordance with 26 U.S.C. 5383 (b)(1). Any unauthorized amelioration or significant alteration of the light transmissibility of the wine will require the reclassification of the wine as a "substandard wine."
All grape wines (that is, wines made solely from grapes) contain sulfites which are derived from the soil and/or added during picking to prevent spoilage. In the wine-making industry, grapes are generally treated with sulfites prior to and after crushing to control undesirable micro-organisms, inhibit browning and serve as an antioxidant. After the fermentation process, sulfites may be added to prevent secondary fermentation. While supplying these benefits during the wine-making process, sulfites offer little, if any, benefit after the wine-making process is completed and may impart undesirable taste qualities to the wine and prevent those who are allergic to sulfites from enjoying the wine.
It is known in the art to employ ion exchange techniques in the decolorization of wines. U.S. Pat. No. 4,775,541 ('541 patent) discloses the steps of passing a wine through a basic anion exchange resin and then through an acidic cation exchange resin to decolorize a generally acidic wine. The '541 patent discloses a preliminary optional step of passing the wine through a carbon filter, for the purpose of removing suspended solids to enhance the longevity of the anion and cation exchange resins. The main objective of the '541 invention is the decolorization of citrus wine. Obviously, decolorization of a standard wine would significantly alter the light transmissibility of the wine, such that the decolorized wine may no longer be classified as a standard wine.
Therefore, a need exists for a method to remove sulfites to enhance the commercial value of standard wine, especially high quality grape standard wines.